This crater isn’t at Petersburg. It’s tucked away on the side of a mountain at Cumberland Gap National Historical Park, at the junction of Tennessee, Virginia, and Kentucky. I had to hike over and snap a photo of it for a slide presentation last week, and I thought you folks might be interested in seeing it and hearing the back story.

Most of us associate Cumberland Gap with the frontier era, but the Gap was an important location in the Civil War, too. It stood at the junction of two Confederate states and a border state, a potential avenue of advance either from Tennessee into Kentucky or vice-versa. It also offered access to railroads that connected Virginia with the western part of the Confederacy.

Confederates seized it early in the war to secure East Tennessee and a route northward into Kentucky, where Unionist refugees were assembling in camps, waiting for an opportunity to return through the Gap and drive the Confederates out of their homeland. One of those Unionists was Samuel P. Carter, member of a prominent early Tennessee family and now commander of a Union brigade.

In 1862 Carter’s brigade was placed under the command of George W. Morgan as part of the Army of the Ohio’s Seventh Division, and that summer these men marched southward for the long-awaited Union attack on the Gap. Rather than assaulting the Confederates head-on from the north, Morgan divided his force in two and crossed the mountains at two gaps to the west, approaching Cumberland Gap from the south. The Confederates evacuated before Morgan arrived, and his troops occupied the Gap on June 18 without the loss of a single man.

They weren’t there for long. When the Confederates advanced northward into Kentucky under Braxton Bragg and Edmund Kirby Smith, Morgan found himself cut off. With dwindling supplies and a Rebel force hovering outside his position, Morgan mined the mountain and then evacuated the Gap almost exactly three months after taking it, leading his men on a harrowing retreat north to the Ohio River through the only avenue of escape open to him. (One of the Union officers present described the capture, occupation, and retreat from the Gap in this letter sent to the New York Times.)

Morgan left a small group of men behind to set fire to the buildings and light fuses to the mines and powder stores. They did so in the wee hours of the morning of September 18. When the powder in the commissary near the base of Tri-State Peak went off, it shook the mountain and sent debris hurtling into the air, an event depicted in this wartime engraving of Morgan’s troops marching northward as explosions tear through the night sky behind them:

From the New York Public Library (Image ID 812927)

The Confederates had to wait a full eighteen hours for the detonations to subside before they could occupy the Union positions. The Rebels maintained control of the Gap for a year after Morgan’s retreat, until Union troops under Ambrose Burnside re-captured it in September 1863. It remained in Union hands for the remainder of the war.

The commissary explosion left a gaping hole in the side of Tri-State Peak. You can access it via a path that joins the Wilderness Road trail near the “Saddle of the Gap,” the point where the road actually passes through the opening in the mountain. Here’s what it looks like:

There’s a wayside marker at the site with a description of the Union evacuation. Have a look the next time you’re in the park, but wear good walking shoes. The trail is a little rough and steep in places.